1. Field of the Invention
The present invention relates generally to methods for stimulating and activating cells, and more particularly, to methods to activate and expand cells using an engineered multivalent signaling platform. The present invention also relates to methods for generating engineered multivalent signaling platform and methods of using same.
2. Description of the Related Art
Immunotherapy involving the priming and expansion of T lymphocytes (T cells) holds promise for the treatment of cancer and infectious diseases, particularly in humans (Melief et al., Immunol. Rev. 145: 167-177 (1995); Riddell et al., Annu. Rev. Immunol. 13:545-586 (1995)). Current studies of adoptive transfer in patients with HIV, CMV, and melanoma involve the infusion of T cells that have been stimulated, cloned and expanded for many weeks in vitro on autologous dendritic cells (DC), virally infected B cells, and/or allogeneic feeder cells (Riddell et al., Science 257:238-241 (1992); Yee et al., J. Exp. Med. 192:1637-1644 (2000), Brodie et al., Nat. Med. 5:34-41 (1999); Riddell et al., Hum. Gene Ther. 3:319-338 (1992), Riddell et al., J. Immunol. Methods 128:189-201 (1990)). However, adoptive T cell immunotherapy clinical trials commonly use billions of cells (Riddell et al., 1995). In order to produce these quantities of cells, many fold expansion of T cells in vitro (e.g., 40 population doublings) is usually required. Furthermore, for optimal engraftment potential and possible therapeutic benefit, it is important to ensure that the T cells, after in vitro expansion, are functional, and not senescent, at the time of re-infusion.
Naturally occurring T cell activation is initiated by the engagement of the T cell receptor/CD3 complex (TCR/CD3) by a peptide-antigen bound to a major histocompatibility complex (MHC) molecule on the surface of an antigen-presenting cell (APC) (Schwartz, Science 248:1349 (1990)). While this is the primary signal in T cell activation, other receptor-ligand interactions between APCs and T cells are required for complete activation. For example, TCR stimulation in the absence of other molecular interactions can induce a state of anergy, such that these cells cannot respond to full activation signals upon restimulation (Schwartz, 1990; Harding, et al., Nature 356:607 (1992)). In the alternative, T cells may die by programmed cell death (apoptosis) when activated by TCR engagement alone (Webb et al., Cell 63:1249 (1990); Kawabe et al., Nature 349:245 (1991); Kabelitz et al., Int. Immunol. 4:1381 (1992); Groux et al., Eur J. Immunol. 23:1623 (1993)).
Multiple receptor-ligand interactions take place between the T cell and the APC, many of which are adhesive in nature, reinforcing the contact between the two cells (Springer et al., Ann. Rev. Immunol. 5:223 (1987)), while other interactions transduce additional activation signals to the T cell (Bierer et al., Adv. Cancer Res. 56:49 (1991)). For example, CD28 is a surface, glycoprotein present on 80% of peripheral T cells in humans and is present on both resting and activated T cells. CD28 binds to B7-1 (CD80) or B7-2 (CD86) and is the most potent of the known co-stimulatory molecules (June et al., Immunol. Today 15:321 (1994), Linsley et al., Ann. Rev. Immunol. 11:191 (1993)). CD28 ligation on T cells in conjunction with TCR engagement induces the production of interleukin-2 (IL-2) (June et al., 1994; Jenkins et al., 1993; Schwartz, 1992). While the exact in vivo role of IL-2 is still in question, there is little doubt that IL-2 is a critical factor for ex vivo T cell expansion (Smith et al., Ann. N.Y. Acad. Sci. 332:423-432 (1979); Gillis et al., Nature 268:154-156 (1977)).
Recently, several new co-stimulatory molecules have been discovered based on their homology with the B7 and CD28 families. PD-1 is expressed on activated T cells and has two B7 like ligands, PD-L1 and PD-L2. Presently, it is unclear whether PD-1 ligation delivers an inhibitory (Freeman et al., J. Exp. Med. 192: 1027-1034 (2000); Latchman et al., Nat. Immunol. 2:261-268 (2001)) or co-stimulatory signal (Dong et al., Nat. Med. 5:1365-1369 (1999); Tseng et al., J. Exp. Med. 193:839-846 (2001)) to T cells. B7-H3, which does not bind to CD28, CTLA-4, ICOS or PD-1, may act as a co-stimulatory molecule for T cell activation and IFN-γ production (Chapoval et al., Nat. Immunol. 2:269-274 (2001)).
The TNF receptor family member 4-1BB (CD137) was initially identified in receptor screens of activated lymphocytes (Pollok, K. E. et al., T cell J. Immunol. 150, 771-781 (1993)). The 4-1BB ligand is expressed by activated B cells, dendritic cells, and monocytes/macrophages, all of which can act as APCs (Goodwin, R. G et al., T cell Eur. J. Immunol. 23, 2631-2641 (1993)). Previous studies have shown that 4-1BB is a co-stimulatory molecule in the activation of T cells, and its signaling is independent from, albeit weaker than, CD28 signaling (Hurtado, J. C., et al., T cell J. Immunol. 158, 2600-2609 (1997); Hurtado, J. C., et al., T cell J. Immunol. 155, 3360-3367 (1995); Saoulli, K. et al., T cell J. Exp. Med. 187, 1849-1862 (1998)). 4-1BB stimulation preferentially activates CD8+ T cells in vitro and amplifies generation of CTL responses in vivo (Shuford, W. W. et al, T cell T cell J. Exp. Med. 186, 47-55 (1997)). The mechanism for this effect may involve improved survival of activated CTLs (Takahashi, C., et al., T cell J. Immunol. 162, 5037-5040 (1999)). Consistent with these data, co-stimulation of 4-1BB has been shown to have anti-viral and anti-tumor effects (Tan, J. T. et al., J. Immunol. 164, 2320-2325 (2000); Melero, I. et al., T cell Nat. Med. 3, 682-685 (1997); Melero, I. et al., Eur J. Immunol. 28, 1116-1121 (1998); DeBenedette, M. A., et al., J. Immunol. 158, 551-559 (1997); Guinn, B. A., et al., J. Immunol. 162, 5003-5010 (1999)).
Co-stimulation of T cells has been shown to affect multiple aspects of T cell activation (June et al., 1994, Supra). It lowers the concentration of anti-CD3 required to induce a proliferative response in culture (Gimmi et al., Proc. Natl. Acad. Sci. USA 88:6575 (1991)). CD28 co-stimulation also markedly enhances the production of lymphokines by helper T cells through transcriptional and post-transcriptional regulation of gene expression Lindsten et al., Science 244:339 (1989); Fraser et al., Science 251:313 (1991)), and can activate the cytolytic potential of cytotoxic T cells. Inhibition of CD28 co-stimulation in vivo can block xenograft rejection, and allograft rejection is significantly delayed (Lenschow et, al., Science 257:789 (1992); Turka et al., Proc. Natl. Acad. Sci. USA 89:11102 (1992)).
Methods of expanding T cell clones and/or lines for adoptive immunotherapy have proven to have certain drawbacks. The standard culture of pure CD8+ cells is limited by apoptosis, diminution of biological function and/or proliferation, and obtaining a sufficient number of cells to be useful has been particularly difficult. Current cell culture techniques may require several months to produce sufficient numbers of cells from a single clone (Riddell et al., 1992; Heslop et al., Nat. Med. 2:551-555 (1996)), which is a problematic limiting factor in the setting of malignancy. Indeed, it is possible that such the T cells that are currently infused into patients, may have a limited replicative capacity, and therefore, could not stably engraft to provide long-term protection from disease. Furthermore, the various techniques available for expanding human T cells have relied primarily on the use of accessory cells (i.e. cells that support or promote T cell survival and proliferation such as PBMC or DC, B cells, monocytes, etc.) and/or exogenous growth factors, such as interleukin-2 (IL-2). IL-2 has been used together with an anti-CD3 antibody to stimulate T cell proliferation. Both primary and secondary APC signals are thought to be required for optimal T cell activation, expansion, and long-term survival of the T cells upon re-infusion. The requirement for accessory cells presents a significant problem for long-term culture systems because these cells are relatively short-lived. Therefore, in a long-term culture system, APCs must be continually obtained from a source and replenished. The necessity for a renewable supply of accessory cells is problematic for treatment of immunodeficiencies in which accessory cells are affected. In addition, when treating viral infection, if accessory cells carry the virus, the cells may contaminate the entire T cell population during long-term culture.
In the absence of exogenous growth factors or accessory cells, a co-stimulatory signal may be delivered to a T cell population, for example, by exposing the cells to a CD3 ligand and a CD28 ligand attached to a solid phase surface, such as a bead. See C. June, et al, (U.S. Pat. Nos. 5,858,358 and 6,352,694); C. June et al., WO 99/953823. The methods currently available in the art have not focused on obtaining a more robust population of T cells and the beneficial results thereof. Furthermore, the applicability of activated and expanded T cells has been limited to only a few disease states. For maximum in vivo effectiveness, theoretically, an ex vivo- or in vivo-generated, activated T cell population should be in a state that can maximally orchestrate an immune response to cancer, infectious disease, or other disease states. While previous investigators have noted long term qualitative persistence of T cells in human adoptive transfer protocols, the quantitative level of sustained engraftment has been low (Rosenberg et al., N. Engl. J. Med. 323:570-578 (1990); Dudley et al., J. Immunother. 24:363-373 (2001); Yee et al., Curr. Opin. Immunol. 13:141-146 (2001); Rooney et al., Blood 92:1549-1555 (1998)).
Therefore, the present invention offers therapeutic advantages because there remains an unmet need for sustained high-level engraftment of human T lymphocytes. Methods of stimulating the expansion of certain subsets of T cells have the potential to generate a variety of T cell compositions useful in immunotherapy. Successful immunotherapy can be aided by increasing the reactivity and quantity of T cells by efficient stimulation. The present invention provides methods to generate an increased number of activated and pure T cells that have surface receptor and cytokine production characteristics that are optimal for T cell-mediated immune responses and that appear more physiologically functional than T cells produced by other expansion methods. In addition, the present invention provides compositions of cell populations of any target cell, including T cell populations and parameters for producing the same, as well as providing other related advantages.